Electric field gradients at (111)In/(111)Cd probe atoms on A-sites in 211-MAX phases
| Autor: | Daniel Jürgens, Michel W. Barsoum, Matthias Nagl, M. Uhrmacher, Mestnik-Filho J, C. Brüsewitz, H. Hofsäss, Ulrich Vetter, H.-G. Gehrke |
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| Rok vydání: | 2011 |
| Předmět: |
Coupling constant
Chemistry 02 engineering and technology 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Ion WIEN2k Ab initio quantum chemistry methods Electric field 0103 physical sciences Quadrupole General Materials Science MAX phases Atomic physics 010306 general physics 0210 nano-technology Stoichiometry |
| Zdroj: | Journal of physics. Condensed matter : an Institute of Physics journal. 23(50) |
| ISSN: | 1361-648X |
| Popis: | The method of perturbed angular correlation (PAC) was applied to selected MAX phases with 211 stoichiometry. Radioactive (111)In ions were implanted in order to measure the electric field gradients (EFG) in the key compounds Ti(2)InC and Zr(2)InC to determine the strength and symmetry of the EFG at the In-site. Further PAC studies in the In-free MAX phases Ti(2)AlN, Nb(2)AlC, Nb(2)AsC and Cr(2)GeC were performed to confirm that the In probes occupy the A-site as well. The strength of the EFG, with a quadrupole coupling constant ν(Q) between 250 and 300 MHz in these phases, is quite similar to the ones found in Ti(2)InC with ν(Q) = 292(1) MHz and in Zr(2)InC with ν(Q) = 344(1) MHz, respectively. Different annealing behavior was observed whereas in all cases a linear decrease of ν(Q) with increasing measuring temperatures was found. The experimental results are also in excellent agreement with those predicted by ab initio calculations using the APW+lo method implemented in the WIEN2k code. This study shows in an exceptional manner that (111)In → (111)Cd atoms are suitable probes to investigate the local surrounding at the A-site in 211-MAX phases. |
| Databáze: | OpenAIRE |
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